• Clinical and Experimental Pediatrics
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• v.48 no.9
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• pp.939-945
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• 2005

Purpose : The purpose of this study was to report outcome of fetal infants with birth weight below 500 g known as lower limit of viability and to evaluate treatment characteristics and short-term morbidity of their survivors. Methods : We retrospectively analyzed the medical records of all fetal infants with birth weight below 500 g who were delivered at Samsung Medical Center(SMC), or transferred to neonatal intensive care unit(NICU) of SMC within 24 hrs after birth between 1994 and 2004. Data for all interventions and morbidity outcome were analyzed for infants who were admitted to the NICU and were compared between NICU survivors and deaths. Results : Among 53 infants with birth weights of 400 to 499 g who were born in SMC during the study period, 8(15.1%) infants were admitted to the NICU and one was transferred to NICU from other hospital. Overall, 4(44%) of 9 survived and were discharged from the NICU. The smallest infant who survived weighed 439 grams. The least gestational age was $23^{+3}$ among the survivors. Compared with NICU deaths, NICU survivors had larger gestational age($24^{+2}{\pm}1^{+3}$ vs. $25^{+4}{\pm}2^{+3}$) and birth weight($424{\pm}17$ vs. $453{\pm}19$)(P<0.05). Median survival duration of NICU deaths was 15 days. None of NICU survivors had severe IVH, but 3(75%) had laser therapy for retinopathy of prematurity and bronchopulmonary dysplasia, respectively. Conclusion : Fetal infants with birth weight below 500 g known as lower limit of viability survived successfully. Study for their long-term follow-up will be needed to define our limit of viability and indication for their active resuscitation.

• Journal of the Korean Geographical Society
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• v.41 no.5 s.116
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• pp.527-544
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• 2006

This study provides a definition of heat waves, which indicate the conditions of strong sultriness in summer, appropriate to Korea and intends to clarify long term(1973-2006) averaged spatial and temporal patterns of annual frequency of heat waves with respect to their intensity. Based on examination of the Korean mortality rate changes due to increase of apparent temperature under hot and humid summer conditions, three consecutive days with at least $32.5^{\circ}C,\;35.5^{\circ}C,\;38.5^{\circ}C,\;and\;41.5^{\circ}C$ of daily maximum Heat Index are defined as the Hot Spell(HS), the Heat Wave(HW), the Strong Heat Wave(SHW), and the Extreme Heat Wave(EHW), respectively. The annual frequency of all categories of heat waves is relatively low in high-elevated regions or on islands adjacent to seas. In contrast, the maximum annual frequency of heat waves during the study period as well as annual average frequency are highest in interior, low-elevated regions along major rivers in South Korea, particularly during the Changma Break period(between late July and mid-August). There is no obvious increasing or decreasing trend in the annual total frequency of all categories of heat waves for the study period However, the maximum annual frequencies of HS days at each weather station were recorded mainly in the 1970s, while most of maximum frequency records of both the HW and the SHW at individual weather stations were observed in the 1990s. It is also revealed that when heat waves occur in South Korea high humidity as well as high temperature contributes to increasing the heat wave intensity by $4.3-9.5^{\circ}C$. These results provide a useful basis to help develop a heat wave warning system appropriate to Korea.

• Sleep Medicine and Psychophysiology
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• v.10 no.1
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• pp.52-60
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• 2003

Objectives: Stage 1 sleep provides important information regarding interpretation of nocturnal polysomnography, particularly sleep onset. It is a short transition period from wakeful consciousness to sleep. The lack of prominent sleep events characterizing stage 1 sleep is a major obstacle in automatic sleep stage scoring. In this study, utilization of simultaneous EEG and EOG processing and analyses to detect stage 1 sleep automatically were attempted. Methods: Relative powers of the alpha waves and the theta waves were calculated from spectral estimation. A relative power of alpha waves less than 50% or relative power of theta waves more than 23% was regarded as stage 1 sleep. SEM(slow eye movement) was defined as the duration of both-eye movement ranging from 1.5 to 4 seconds, and was also regarded as stage 1 sleep. If one of these three criteria was met, the epoch was regarded as stage 1 sleep. Results were compared to the manual rating results done by two polysomnography experts. Results: A total of 169 epochs were analyzed. The agreement rate for stage 1 sleep between automatic detection and manual scoring was 79.3% and Cohen’s Kappa was 0.586 (p<0.01). A significant portion (32%) of automatically detected stage 1 sleep included SEM. Conclusion: Generally, digitally-scored sleep staging shows accuracy up to 70%. Considering potential difficulty in stage 1 sleep scoring, accuracy of 79.3% in this study seems to be strong enough. Simultaneous analysis of EOG differentiates this study from previous ones which mainly depended on EEG analysis. The issue of close relationship between SEM and stage 1 sleep raised by Kinnari remains a valid one in this study.

• Childhood Kidney Diseases
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• v.17 no.1
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• pp.19-24
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• 2013

Purpose: Recently, enterococcus spp. have become one of the most common nosocomial pathogens with increasing rates of multi-drug resistance. However, study on enterococcal urinary tract infections (UTIs) in children is very limited, especially community acquired UTIs. We studied the clinical characteristics of enterococcus spp. in community acquired UTIs and antibiotic resistance within our urban area. Methods: All children with first episode of community acquired UTIs due to enterococcus spp. and Echerichia coli who were admitted in Pusan National University Children's Hospital between January 2010 and January 2013 were included in our study. We retrospectively reviewed their medical records. Results: During the study period, 201 patients were identified to have first episode of community acquired UTIs. 154 cases were E.coli UTIs (76.6%) and 11 cases were enterococcal UTIs (5.5%) and all enterococcus spp. were Enterococcus feacalis. In enterococcal UTI group, voiding cystourethrogram(VCUG) was performed in 7/11 patients and demonstrated 4 vesicoureteral refluxes (VURs) with renal scar and 3 patients underwent corrective surgery. In E.coli UTI group, VCUG was performed in 121/154 patients and demonstrated 23 VURs and 11 patients underwent corrective surgery. Enterococcal group had significant high rate of underlying urinary abnormalities and surgical corrections compared with E. coli group. All enterococcus spp. were susceptible to ampicillin, vancomycin and linezolid, but all were resistant to tetracycline. They also showed 71.4% resistance to trimethoprim-sulfamethoxazole and 20% resistance to ciprofloxacin. Conclusion: Community acquired enterococcal UTIs in children were rare within our urban area. However, they could be indicative of severe underlying urinary tract abnormalities.

• Pediatric Infection and Vaccine
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• v.21 no.2
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• pp.129-138
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• 2014

Purpose: Streptococcus pyogenes is an important cause of invasive diseases in children. We aimed to describe the clinical characteristics of invasive infections due to S. pyogenes in children in Korea. Methods: A retrospective study of children under 18 years of age with invasive infections due to S. pyogenes at Seoul National University Children's Hospital between March 1992 and December 2012, and Seoul National University Bundang Hospital between March 2003 and December 2012 was conducted. Demographic factors, clinical characteristics, laboratory findings, treatment, mortality and morbidity of all patients were reviewed. Results: A total of 30 among 36 cases identified as invasive disease due to S. pyogenes were available for review. There was a predominance for male subjects (male:female=2.75:1). The median age was 50 months (range 12 days to 15 years) and 53.3% were under 5 years of age. Skin and soft tissue infections (9/30, 30.0%), bacteremia without identified focus (4/30, 13.3%) and bone and joint infections (6/30, 20.0%) were the most frequent clinical presentations. Streptococcal toxic shock syndrome (3/30, 10.0%) pulmonary, abdomen and central nervous system infections (2/30, 6.7%) were also seen. There was a peak in number of patients in year 2012 (9/30, 30.0%). There were no cases of mortality. Erythromycin and clindamycin resistance rates were low by 3.8% and 7.5%, respectively. Conclusion: We studied the clinical presentations of invasive infections due to S. pyogenes during the past 20 years in Korean children. The findings of this study help us understand the characteristics of the disease, enhancing early recognition and prompting adequate antibiotic therapy which is important in reducing morbidity and mortality.

• Korean Journal of Animal Reproduction
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• v.25 no.3
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• pp.207-217
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• 2001

Diagnosis and treatment of major reproductive failures were carried out for 836 dairy cows of 12 farms in Kimje area from May 1999 to May 2000. Reproductive failures were classified into four categories: uterine diseases, ovarian diseases, combination of uterine and ovarian diseases, and anestrus with corpus luteum (CL), based on the diagnosis by both rectal palpation and ultrasonography (SA 600, Medison, 5.OMHz transducer). 1. Of 102 cows examined, 15 cows were diagnosed as pregnant. Cows with real reproductive failures were therefore 87 cows and the rate of reproductive failures far all the cows of 12 farms was 10.4% (87/836). 2. Of 57 cows with reproductive failures, the cows with uterine diseases were 33 heads (37.9%), with ovarian diseases: 30 heads (34.5%), with combination form: 16 heads (18.4%), and with anestrus with CL: 8 heads (9.2%). 3. Of 87 cows with reproductive failures, 7 cows were slaughtered and 80 cows were treated by hormone or douche. The cows expressed estrus were 74 cows (92.5%, 74/80 heads) and 56 cows were pregnant (70.0%, 56/80 heads) following treatment. 4. The reproductive failures tended to be increased as the period proceeded from 30 days (2.3%, 2/87 heads) to over 120 days (56.3%, 49/87 heads) after parturition. 5. Associated other diseases to reproductive failures were foot diseases(5 cows), joint diseases (5 heads), urovagina (6 heads), and rectovaginal fistula (2 cows) and the rate of occurrence of associated diseases was 20.7% (18/87 heads). 6. No reproductive record was used in 7 farms of 12 farms and 5 farms had no play ground or not used for the cows. These results indicated that diagnosis fur reproductive failures by rectal palpation along with ultrasonography was more accurate than the conventional rectal palpation and brought better result of treatment for major types of reproductive failures. It was also indicated that non-uses of reproductive record and play ground were also important factors in occurrence of reproductive failures.

• Clinical and Experimental Pediatrics
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• v.51 no.11
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• pp.1158-1164
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• 2008

Purpose : To investigate the discriminative ability of pediatric index of mortality 2 (PIM2) and pediatric risk of mortality III (PRISM III) in predicting mortality in children admitted into the intensive care unit (ICU). Methods : We retrospectively analyzed variables of PIM2 and PRISM III based on medical records with children cared for in a single hospital ICU from January 2003 to December 2007. Exclusions were children who died within 2 h of admission into ICU or hopeless discharge. We used Students t test and ANOVA for general characteristics and for correlation between survivors and non-survivors for variables of PIM2 and PRISM III. In addition, we performed multiple logistic regression analysis for Hosmer-Lemeshow goodness-of-fit, receiver operating characteristic curve (ROC) for discrimination, and calculated standardized mortality ratio (SMR) for estimation of prediction. Results : We collected 193 medical records but analyzed 190 events because three children died within 2 h of ICU admission. The variables of PIM2 correlated with survival, except for the presence of post-procedure and low risk. In PRISM III, there was a significant correlation for cardiovascular/neurologic signs, arterial blood gas analysis but not for biochemical and hematologic data. Discriminatory performance by ROC showed an area under the curve 0.858 (95% confidence interval; 0.779-0.938) for PIM2, 0.798 (95% CI; 0.686-0.891) for PRISM III, respectively. Further, SMR was calculated approximately as 1 for the 2 systems, and multiple logistic regression analysis showed ${\chi}^2(13)=14.986$, P=0.308 for PIM2, ${\chi}^2(13)=12.899$, P=0.456 for PRISM III in Hosmer-Lemeshow goodness-of-fit. However, PIM2 was significant for PRISM III in the likelihood ratio test (${\chi}^2(4)=55.3$, P<0.01). Conclusion : We identified two acceptable scoring systems (PRISM III, PIM2) for the prediction of mortality in children admitted into the ICU. PIM2 was more accurate and had a better fit than PRISM III on the model tested.

• Pediatric Infection and Vaccine
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• v.11 no.1
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• pp.112-120
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• 2004

Purpose : Methicillin Resistant-Coagulase Negative Staphylococcus(MR-CNS) infection has become an increasingly important cause of morbidity in NICU infants. We investigated the c linical characteristics of MR-CNS sepsis. Methods : This study included 40 neonates with MR-CNS sepsis who were admitted to the neonatal intensive care unit of Kangnam Sacred Heart Hospital, Hallym University from January 1998 to July 2002. MR-CNS sepsis was defined as MR-CNS recovery from blood with clinical symptoms and signs of infection. Retrospective analyses of the medical records of patients with MR-CNS sepsis were performed. The analyses included demographic findings, clinical features, hospital courses, risk factors for infection including invasive procedures and mortality. Results : From 1998 to 2002, there were 40 cases of MR-CNS sepsis, comprising 17.7% of late onset infections in NICU of Kangnam Sacred Heart Hospital. The male/female ratio was 1.5 : 1. The mean gestational age of infected babies was $32.4{\pm}4.3$ weeks at birth. And the first positive MR-CNS culture was done in the day $10.6{\pm}9.3$ after birth. Clinical symptoms such as fever, dyspnea, cyanosis, grunting, bradycardia, vomiting and diarrhea were frequent in MR-CNS. Mechanical ventilation was applied in 12 cases and catheter was inserted in 11 cases. The mortality(12.5%) directly attributable to MR-CNS sepsis was similar to other late onset infections. Conclusion : MR-CNS is a pathogen responsible for most late onset and nosocomial infections. And it will be life-threatening in high-risk neonate. Awareness of increasing infections due to MR-CNS in NICU is important not only for infection control but also placing a great limit in use of antibiotics and invasive procedures, especially in premature infants.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.14 no.4
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• pp.357-365
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• 2016

We observed the ${\gamma}-ray$ shielding characteristics and compressive strength of five types of concrete using general aggregates and high-weight aggregates. The aggregates were classified into fine aggregate and coarse aggregate according to the average size. The experimental results obtained an attenuation coefficient of $0.371cm^{-1}$ from a concrete with the oxidizing slag sand (OSS) and oxidizing slag gravel (OSG) for a ${\gamma}-ray$ of $^{137}Cs$, which is improved by 2% compared with a concrete with typical aggregates of sand and gravel. In the unit weight measurement, a concrete prepared by iron ore sand (IOS) and OSG had the highest value of $3,175kg{\cdot}m^{-3}$. Although the unit weight of the concrete with OSS and OSG was $3,052kg{\cdot}m^{-3}$, which was lower than the maximum unit weight condition by $123kg{\cdot}m^{-3}$, its attenuation coefficient was improved by $0.012cm^{-1}$. The results of chemical analysis of aggregates revealed that the magnesium content in oxidizing slag was lower than that in iron ore, while the calcium content was higher. The concrete with oxidizing slag aggregates demonstrated enhanced ${\gamma}-ray$ shielding performance due to a relatively high calcium content compared with the concrete with OSS and OSG in spite of a low unit weight. All sample concretes mixed with high-weight aggregates had higher compressive strength than the concrete with typical sand and gravel. When OSS and IOS were used, the highest compressive strength was 50.2 MPa, which was an improvement by 45% over general concrete, which was achieved after four weeks of curing.

• Journal of the Speleological Society of Korea
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• no.95
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• pp.35-49
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• 2009

Ever since the beginning of time, caves not only have offered a place to live for humans but they have also been used as cultural spaces. That is, in the event of making some sounds in a location within the cave, the sound that is created is greatly magnified and sounds out as if it is being amplified from a giant megaphone. This, as we well know it, is known as the resonance effect. Here, the cave itself appears to function as a massive wind instrument. Especially in cases like the Altamira Cave (Spain) where cave paintings were found, the point where the cave drawings were found has commonalities in that it is a wide space and that it is usually discovered together with flutes and drums that are made with mammoth bones. We need to focus on this point. We can infer from these facts that the prehistoric people have carried out cultural activities along with their incantation rituals within those caves. In the meantime, amongst the Korean traditional arts, in the case of pansori which is a representative vocal genre, there have been examples where caves were used as practicing locations for those people who are training to perfect their singing. This is known as toguldoggong(土窟獨功) which literally means 'obtaining one's own art by oneself in the earth cave by practicing incessantly'. This process along with pokpodoggong (瀑布獨功) (same as above except that the location is by the waterfall) is the final training stage in order to become a recognized virtuoso on the part of the apprentice. This could be compared to the final annealing and finishing process of producing a metalwork. This has been a long tradition followed by most Korean traditional artists in order to perfect their sound which is harmonious with nature within natural surroundings. By honing in on this point, I have come to think about this matter repeatedly while coaching the university students in vocal singing. In short, I came to the conclusion that "the making of natural sounds will be obtained naturally within natural surroundings like caves!" Consequently, The Society for Studying Cave Sounds was inaugurated on January 1992 along with some of my students. We made use of times like vacations to go around exploring caves all over Jeju and carried out investigations of sounds along with cave exploration on an experimental basis. After 5 years, in September of 1997, we were able to host the first ever cave concert domestically at the Whale Nostril Cave(東岸鯨窟) on Wu-do. After that, we have been hosting the cave concert once every year. We have achieved a record of a total of 14 cave concerts until 2009 of this year. Out of these, 2 were held in Seokhwaeam Cave in Kangwon Province, another two were held in Manjang Cave which is a lava cave, and the remaining 10 were held in the Whale Nostril Cave of Wu-do. Along with that, I have carried out a special recording for the production of a cave music CD in May of 1999. This paper was written and organized by using the main materials that were derived from the experiences of using caves as concert halls in the past. It is hoped that this cave concert will offer a very unique experience to tourists who come to Jeju every year and give them the best possible superior natural sound effect that only Jeju caves can offer.